I've got a few more details on these cranks from the 2012 Shimano dealer catalogue that I picked up at Eurobike this week. I still can't find a product page for them on Shimano's website, so here's the info:
Weight: 1772 grams inclg. BBs (FSA's SLK tandem cranks are listed as 1787g, Gossamers are 1972g).
Lengths: 170 or 175 for captain and stoker (although the above post suggests that some importers may unfortunately not offer the 170mm captain cranks).
Chainline: Drive-side = 45mm, Timing-side = 49.9mm (FSA uses 53mm on the timing side).
Colour: Dark grey like the new 2012 Ultegra group. The styling and finish is just like that of the new Ultegra, but instead of having the Ultegra logo, it just says "Shimano" on each crank.
Chainring BCD: Confrimed as 130mm for non-drive and 130mm for drive-side, with a special middle ring that the inner ring attaches to with a BCD of 92mm.
They are also appearing on more retailers websites, with Chain Reaction in the UK listing the captain's cranks for 175 UKP and the stoker's for about 400 UKP. However, they don't expect to receive any stock until December. They are showing 170mm captain cranks as one of the options.
Last edited by Chris_W; 09-05-11 at 06:45 AM.